In an optical disk, address information is preformatted so that an optical disk recording/reproducing device can recognize recording/reproduction-use regions (sectors).
Various methods for preformatting the address information are available and known. Among such methods, a so-called address information multiple-recording method whereby an address information signal indicative of a certain sector is recorded several times is known as a preformatting method with which reproduction and establishment of address information can be improved.
In the case where address information is recorded only once upon random access to an optical disk, if reproduction of the same becomes impossible due to errors occurring to preformatted address information, the finding of a target sector becomes impossible, resulting in that information cannot be recorded/reproduced into/from the foregoing sector.
On the other hand, as described above, multiple recording of address information enables recording/reproduction of information in a sector even if an error occurs to a piece of address information indicative of the sector, since the sector can be recognized as long as another piece of the same address information can be reproduced.
Even with the multiple recording of address information as described above, it often takes place that address information cannot be accurately read by means of a conventional optical disk recording device.